You don't say what version of Audition you use. The last post shows some remarkable advancement over what I use, 3.01, and while interesting may not be very helpful. But it does illustrate the envelope thing. Depending on your patience it works well.

You could try to shape a Dynamic Processing curve to do the same thing and it might be easier that manipulating the envelope points.

These are some screen shots of one curve I cobbled together to raise very low spoken word/banter between tunes that also limits occasional clapping or tuning bits. The low levels are raised and those parts that are well above the zone that I want to raise... are limited to a manageable top end.

This tool is not very subtle so you'll want to experiment with slopes that transition in and out of your target zones. If you get too quick between levels the result will be choppy to one degree or another. For what you say you want to do, I'd work with the applause sections only and leave the music to its own dynamic. Once you have the audience knocked down, you can raise the whole file and perhaps get where you want to be.

I use this tool to address "ass clappers" in the audience as well and have discussed it elsewhere here 'bouts.

Good Luck

Play around, go nutz. Have fun.

(Sorry for the largish pix. If you want a blow by blow explanation, shoot me a PM)